The Algerian security forces have sent hundreds of officers to the southern town of Berriane to end three days of fighting between Arabs and Berbers.
Two people have reportedly been killed in clashes between rival gangs of hooded young men in the Saharan town.
A number of homes and shops have been petrol-bombed.
Correspondents say long-running tensions between Arabs and Berbers in Algeria have been worsened by high unemployment and a shortage of housing.
"The town is in turmoil, but it is controllable," provincial governor Yahia Fehim told Reuters news agency.
Ethnic Berbers claim to pre-date the Arabs, who now account for the majority in Algeria, and are concentrated in two provinces of the north-eastern Kabylie region.
According to varying estimates, they account for between a third and a fifth of Algeria's population of 30 million, and they have campaigned for greater rights since the country won independence from France in 1962.